Adjustable and modular backplane assembly for providing a fiber-optics communication backplane

ABSTRACT

A modular and adjustable backplane assembly for providing a fiber-optics backplane interface to a plurality of router cards functioning as a data router is provided. The assembly includes a first portion having a first array of connectors for interfacing with a compatible array of second connectors engaging specific ones of the router cards, and a second portion having a second array of connectors for interfacing with a compatible array of second connectors engaging specific others of the router cards. The mechanics of the assembly enable a moveable attachment with respect to the first and second portions such that they may be positionally adjusted during mounting, and wherein external data paths are provided from individual ones of the connectors to individual others of the connectors by fiber-optic conductors.

FIELD OF THE INVENTION

[0001] The present invention is in the field of backplane communicationand pertains more particularly to a fiber-optics backplane for ascalable router.

BACKGROUND OF THE INVENTION

[0002] In the general state of the art of electrical and electronicsystems housed in cabinets (often termed chassis), there are typicallyinputs and outputs to the system, facilitated by connection ofcommunication links of various sorts, over which signals are receivedand sent. There are also numerous situations wherein groups ofcomponents in a chassis have to be connected to and communicate withother groups of components internally. Data routers in packet networks,such as the well-known Internet, are a good example. In description inthis specification a data router is used as a specific example of such asituation, and the present invention in several aspects is applicable tosuch routers.

[0003] Transmission of network data traffic is accomplished with the useof data routers as introduced above. A physical data routing machinetypically consists of a processing unit or multiple units which arehoused in a chassis and which communicate with each other and with otherdata routing machines.

[0004] In prior art, one method for achieving communication betweenprocessing units in a single chassis, such as in a data router, involvesthe use of an electrical backplane. When communication between multiplechassis is required, the electrical backplanes of the chassis have beenconnected by cables. The electrical backplane is commonly implemented asa printed circuit board assembly which provides electrical connectivitybetween processing units.

[0005] Noting that it may sometimes be desirable to communicate atbackplane level between elements that are not closely physicallyassociated, such as between elements that may be mounted in separatephysical electronic cabinets, there is a potential problem withelectrical backplanes. When an electrical signal is transmitted overrelatively long distances, for example, deterioration of the signal mayoccur for any of several reasons. For example, longer signal pathsnecessarily present additional resistance. Also, longer paths presentadditional opportunity for interference. Therefore, in order to transmitclean signals in systems utilizing electrical backplanes the elements incommunication must be in relatively close physical proximity to oneanother, such as in the same cabinet.

[0006] Another drawback to electrical backplane boards is that they arerelatively difficult to service. One reason is that the conductors forthe electrical signals are typically patterned on the board, andindividual conductors (signal paths) cannot be separately serviced. Inmany cases the backplane boards are also hardwired to other components.Because any change or repair is normally via a replacement of the entirebackplane, the system containing the electrical backplane is generallyout of service during any backplane service.

[0007] What is clearly needed is an apparatus and method enablingcleaner data signal transmission between router processing units whileat the same time facilitating easier manufacturing and off-lineservicing of backplane assemblies.

SUMMARY OF THE INVENTION

[0008] In a preferred embodiment of the present invention a modular andadjustable backplane assembly to provide backplane communication betweena first signal interface to a first set of components in a cabinet and asecond signal interface to second set of components in the same cabinetis provided, comprising a first portion mounting a third signalinterface configured to engage the first signal interface, a secondportion mounting a fourth signal interface configured to engage thesecond signal interface, an adjustment mechanism allowing relativemovement between the first and second portions, thereby between thethird and fourth signal interfaces, while preserving the modularity ofthe backplane assembly, and a signal conductor assembly engaging thethird and fourth signal interfaces to communicate signals between thefirst set of components and the second set of components.

[0009] In a preferred embodiment the cabinet houses elements of a packetrouter, and the first and second sets of components are router cards. Insome embodiments the first and second signal interfaces are groups ofconnectors for connecting signal conductors to individual ones of thecards in the first and second sets of router cards. Further, the firstand second signal interfaces may be first and second connectors toprinted circuit boards (PCBs) that are in turn connected to the firstand second set of components.

[0010] In some cases the third and fourth signal interfaces comprisefiber-optic connectors, and the signal conductor assembly comprises oneor more fiber-optic fibers having end-connectors for engaging thefiber-optic connectors. The fibers may comprise one or more bundles,ribbons or cables.

[0011] In some cases the third and fourth signal interfaces compriseelectrical connectors, and the signal conductor assembly comprises oneor more cables of electrical conductors having end connectors to engagethe electrical connectors. Also in some cases the signal conductorassembly comprises a cable of electrical conductors havingend-connectors to engage the electrical connectors at the PCBs.

[0012] In some embodiments of the backplane assembly the adjustmentmechanism comprises telescopic engagement elements allowing adjustmentof separation between the first and second portions. The re may furtherbe a locking mechanism for securing the telescoping first and secondportions after adjustment to engage the first and second interfaces.

[0013] In other embodiments the adjustment mechanism further comprisesfirst locating elements in the immediate area of each of the first andsecond signal interfaces, and compatible locating elements in theimmediate area of the third and fourth signal interfaces, to physicallylocate the first and second portions in assembly to the cabinet toengage the first and third and the second and fourth signal interfaces.The locating elements may comprise male and female elements forconstraining engagement position.

[0014] In another aspect of the invention a method for connecting afirst signal interface connected to a first set of components and asecond signal interface connected to a second set of components in acabinet, comprising the steps of (a) preparing a modular and adjustablebackplane assembly comprising a first portion mounting a third signalinterface configured to engage the first signal interface, a secondportion mounting a fourth signal interface configured to engage thesecond signal interface, an adjustment mechanism allowing relativemovement between the first and second portions, thereby between thethird and fourth signal interfaces, while preserving the modularity ofthe backplane assembly, and a signal conductor assembly engaging thethird and fourth signal interfaces to communicate signals between thefirst set of components and the second set of components; and (b)assembling the modular backplane assembly to the cabinet, with the thirdsignal interface engaging the first, and the fourth signal interfaceengaging the second, the adjustment mechanism allowing the third andfourth signal interfaces to assume a proper separation distance toaccomplish engagement of the signal interfaces.

[0015] In some embodiments the cabinet houses elements of a packetrouter, and the first and second sets of components are router cards. Inthese embodiments the first and second signal interfaces may be groupsof connectors for connecting signal conductors to individual ones of thecards in the first and second sets of router cards. Also in someembodiments the first and second signal interfaces may be first andsecond connectors to printed circuit boards (PCBs) that are in turnconnected to the first and second set of components. Further, in someembodiments the third and fourth signal interfaces comprise fiber-opticconnectors, and the signal conductor assembly comprises one or morefiber-optic fibers having end-connectors for engaging the fiber-opticconnectors. The fibers may comprise one or more bundles, ribbons orcables. In some cases the third and fourth signal interfaces compriseelectrical connectors, and the signal conductor assembly comprises oneor more cables of electrical conductors having end connectors to engagethe electrical connectors. Also in some cases the signal conductorassembly comprises a cable of electrical conductors havingend-connectors to engage the electrical connectors at the PCBs.

[0016] In some embodiments the adjustment mechanism comprises telescopicengagement elements allowing adjustment of separation between the firstand second portions, and there may further be a locking mechanism forsecuring the telescoping first and second portions after adjustment toengage the first and second interfaces. In addition there may be firstlocating elements in the immediate area of each of the first and secondsignal interfaces, and compatible locating elements in the immediatearea of the third and fourth signal interfaces, to physically locate thefirst and second portions in assembly to the cabinet to engage the firstand third and the second and fourth signal interfaces. The locatingelements may comprise male and female elements for constrainingengagement position.

[0017] In another aspect there may be a fifth signal interface connectedto one or both of the third and fourth signal interfaces, the fifthsignal interface placed on the backplane assembly to be accessible withthe backplane assembly mounted to the cabinet, to facilitate connectionof the backplane assembly to a second backplane assembly having a fifthsignal interface and assembled to a second cabinet, thereby providingsignal communication between components in the first cabinet and thesecond cabinet. The fifth signal interface may be a connector forconnecting one or more signal conductors, and may comprise a fiber-opticconnector compatible with a mating connector for one or more fiber-opticfibers between the backplane assemblies. The fiber-optic fibers can bein one or more ribbons or cables.

[0018] In yet another embodiment the fifth signal interface is anelectrical connector compatible with a mating connector of an electricalcable between the backplane assemblies.

[0019] In embodiments of the invention taught in enabling detail below,for the first time an adjustable cabinet backplane is provided to theart, in which regions of the backplane may be positioned in assemblyaccording to the positions of elements of the cabinet to which thebackplane is to be assembled. Also for the first time an ability tointerconnect elements in each cabinet at the backplane level isprovided.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0020]FIG. 1a is a perspective view of a backplane assembly according toan embodiment of the present invention as seen from a first vantagepoint.

[0021]FIG. 1b is a perspective view of a backplane assembly according toan embodiment of the present invention as seen from a second vantagepoint.

[0022]FIG. 2 is a perspective view of the backplane assembly of FIG. 1shown disassembled.

[0023]FIG. 3 is a block diagram illustrating the relationship betweenthe backplane assembly of FIGS. 1 and 2 to a main router chassisaccording to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024]FIGS. 1a and 1 b are perspective views of a backplane assembly 100according to an embodiment of the present invention as seen from twoseparate vantage points. Backplane assembly 100 comprises separate topand bottom components or portions represented herein as components 105and 106 that can be assembled together and whose clearance tolerancefrom each other can be adjusted via a telescopic or slidable method.Telescopic clearance is illustrated in this example by a bidirectionalarrow labeled Telescopic Clearance. Both components 105 and 106 makingup backplane 100 are, together, mounted to a back panel illustratedherein as back panel 101. Back panel 101 has plurality of openingsprovided therein and adapted for accepting fasteners as may be found incurrent art to secure the connection of backplane assembly or backplane100 to a router chassis.

[0025] Referring now to FIG. 1b, backplane 100 has a plurality ofopenings provided therein and adapted to house a plurality of fabriccard (FC) connectors 102. These connectors comprise a communicationsignal interface to a set of fabric cards. Connectors 102 are containedin portion 106 of backplane assembly 100. Connectors 102 are, in thisparticular embodiment plastic plug-in connectors arranged in a Cartesianarray, which is designed to match the positions of fabric card terminalsof fabric cards housed in a card cage in a data router chassis (notillustrated). Backplane 100 also has a plurality of line card (LC)fiber-optics connectors 103 provided therein, that comprise anothersignal interface, this time to line cards. Connectors 103 are arrangedin the top portion of backplane assembly 100. Like fabric-cardconnectors 102, they are plastic plug-in connectors. Connectors 103 arearranged in a row matching the pattern of connectors on line cardsinstalled in a main router chassis.

[0026] The structure for backplane assembly 100 (portions 105 and 106)may be manufactured from aluminum, sheet metal, or other durablematerial that may be formed and machined. Similarly, panel 101 may bemanufactured from aluminum or other sheet metals.

[0027] In this example, backplane connections are implemented usingfiber optics ferrules well-known in the art. In other embodiments of theinvention the connectors on the signal interfaces can be for electricalsignals. Connector housings 102 and 103 function to mechanically houseeither the female or alternatively, the male ferrule. Each ferrulepresents optic strands or fibers, which are strategically aligned by theconnection method so that data may be transmitted between the strands.In actual practice in a preferred embodiment, each connector housing(102, 103) contains 4 optics ferrules either male or female. Cardterminals (not shown) within a router chassis contain 4 ferrules, whichmate with the ferrules in connector housings 102 and 103. If theferrules on the router card terminals are male, then the ferrules on theconnector housings will be female.

[0028] Intercommunication between router cards then is facilitated byconnectors 102 and 103 comprising an “optics backplane”. Unlike aphysical electrical backplane board of prior art, fiber strandscomprising communication paths interconnect specific ferrules containedin the housings enabling cross communication among cards housed in themain router chassis. Similarly, ferrules provided in separate routerchassis may be connected by fiber-optics, enabling a fabric card housedin one router chassis to communicate with a similar card housed in aseparate router chassis essentially providing a scalable router. Theimplementation of fiber-optic communication as a backplane enablesmultiple router chassis integrated by backplane communication to formone router to be located much further apart than is practical withprior-art electrical back-planing methods.

[0029] In the example of FIG. 1, backplane assembly 100 has 4 alignmentopenings 104 provided therein and adapted to accept alignment pins ordowels (not shown) provided in a main router chassis. Alignment openings104 are strategically located in four strategic locations on thebackplane assembly 100, two on the top portion and two on the bottomportion. Openings 104 are somewhat larger in diameter than thecorresponding diameter of alignment pins or dowels on a router chassis.The oversizing enables acceptance of the alignment pins of a routerchassis without causing misalignment of connectors.

[0030] As was described above, backplane assembly 100 in this exampleconsists of two portions 105 and 106 that are assembled together in aslidable fashion, providing an adjustment mechanism, enabling bothvertical and some horizontal float. When back panel 101 is completelyinstalled to backplane assembly 100, the slidable position with respectto portions 105 and 106 of the assembly is locked. The goal oftelescopic capability as an adjustment mechanism is to enable alignmentopenings 104 to be conditionally tolerenced to fit over fixed alignmentpins housed in any main router chassis. It is noted herein that thealignment pins in a router chassis are associated carefully to the trueposition of fabric and line card connectors presented for engagingconnectors 102 and 103 respectively, such that when backplane 100 isadjusted for fit over the alignment pins, all of the optics connectionsare aligned for plug-in. The dimensional variance may change somewhatfrom chassis to chassis. Therefore, provision of an adjustable backplaneassembly provides modularity.

[0031]FIG. 2 is a perspective view of the backplane assembly 100 ofFIGS. 1a and b shown disassembled illustrating separate components 105and 106.

[0032] This disassembled view illustrates the mechanism of thetelescopic capability of backplane assembly 100. Component or upperportion 105 houses connectors 103 while component or lower portion 106houses connectors 102. Backplane assembly 100 is illustrated in thisexample without back panel 101 of FIG. 1 in order to reveal alignmentslots that enable telescopic adjustment. For example, lower portion 106has 3 alignment slots provided therein and labeled “hardware locations”.These alignment slots correspond to a matching array (3) of alignmentslots provided in upper portion 105. Each alignment slot is elongated toprovide the vertical float adjustment described with reference to FIG. 1above. Upper portion 105 may be manufactured of such a width dimensionso as to fit inside portion 106 or so as to fit over portion 106. Thealignment slots are adapted to fit around a common fastening hardwaresuch as bolts.

[0033] In one embodiment, metal inserts (not shown) may be used toprovide an adjustment mechanism at the location of each alignment slot.Such inserts are loosened to allow float capability along the elongatedslots until suitable match up of alignment openings 104 (FIG. 1) withmatching alignment pins on a router chassis is achieved. With alignmentaccomplished, meaning that openings 104 are successfully mated withcorresponding alignment pins provided in a main router chassis, thetelescopic fasteners can be tightened securing the aligned positioningand backpanel 101 (FIG. 1) may then be installed.

[0034]FIG. 3 is a block diagram illustrating the relationship ofbackplane assembly 100 to a main router chassis 300 according to anembodiment of the present invention. Again, the adjustable backplaneassembly in various embodiments may be for connection of elements inmany sorts of cabinets and systems, of which packet routers are a singleexample.

[0035] Main router chassis 300 houses a card cage 301. Card cage 301 isadapted to support a line card array 302 and a fabric card array 306. Itis noted herein that line cards 302 and fabric cards 306 of routerchassis 300 are supported within cage 301 in a fashion similar to booksbeing stacked along side each other at equal spacing from each other.Each card rests in a card slot (not illustrated). The card slots areprovided equally spaced from one another, the cards adapted individuallyto fit snugly into a designated slot. It is also noted herein that acomparatively few control cards (not illustrated) are, in actualpractice, included in line card array 302.

[0036] Exposed Fiber-optics connectors, illustrated herein asfiber-optics connectors 303 (for line cards) and fiber-optics connectors304 (for fabric cards) are in true-position relationship with respect toone another when the cards are installed in their respective slots.Fiber-optics connectors 304 and 303 fit easily through provided openingsmachined into or provided in a separate piece like a grate that ismounted onto main router chassis 300. It is noted herein that thepattern of openings provided for fitting card terminals there throughhas all individual openings oversized with respect to inner dimensioningto accept the plastic connector housings in a slip-through fashion.However, the pattern of openings provided on backplane 100 compriseindividual openings that are tightly-toleranced. Each line card andfabric card has, in addition to fiber-optics connectors 304 and 303,connectors 305 to facilitate plug-in connection to conventionalelectrical backplane boards, labeled as such, which are installed inmain chassis 300. It is noted herein that electrical backplanes arestill used in this example for propagating error messaging and othersuch signals.

[0037] In various applications the backplane assembly may be implementedas an electrical backplane or as a fiber-optic backplane. However,fiber-optics is used in this example to transmit information related todata packets from card to card along with certain other message types.Fiber-optics FC and LC connectors provided on housing 100 are analogousto connectors 102 and 103 respectively of FIG. 1. In this example one ormore fiber-optics cables, represented by element number 310, connect theupper and lower signal interfaces (the fiber-optic connectors 102 and103, see FIG. 1a and b). This cable or cables are provided withsufficient slack that the necessary adjustment can be made between theupper and lower portions of the backplane assembly. In the case of anelectrical backplane this cable or cables comprise cables of electricalconductors.

[0038] In one embodiment, especially useful in an electrical backplane,separate PCBs may be mounted at the upper and lower signal interfaces,and cable connection 310 is accomplished between these PCBs. In thisembodiment the connection PCBs may be considered a part of signalinterfaces 102 and 103.

[0039] When backplane assembly 100 is in a loosened andvertically-adjustable mode, alignment openings 104 (FIG. 1) are placedover the alignment pins (not illustrated) of chassis 300. At this pointline card connectors 103 (Optics (LC)) and fabric card connectors 102(Optics (FC) are in proper alignment to be presented to line cardconnectors 303 and fabric card connectors 304 respectively. Housing 100fits to chassis 300 generally in the direction of the illustrateddirectional arrows.

[0040] Backplane assembly 100 has a built-in vertical clearance areadesigned to allow enough room for the router's lower electrical board305 when the optics backplane assembly 100 is installed to chassis 300.This area is illustrated herein by the arrows labeled Clearance forfitting over Electrical Board. Also shown are cooling fans housed in thetop and bottom sections of the main router chassis 300. Cooling fans arefor dispersing heat generated by processing.

[0041] Removal of a Backplane Assembly:

[0042] Referring now to FIG. 3, it is again noted herein that eachfabric card (306) and line card (302) fits into card cage 301 aspreviously described with respect to the main router housing (300) sothat the method of unplugging and disconnecting a card from a mountedbackplane assembly is to simply pull the card out from its slot similarto removing a modular PC card from a PC slot. To remove the entirebackplane assembly itself from the router chassis, all of the line cardsand fabric cards are physically pulled from their connections to theoptics backplane assembly and can remain aligned in their slots.Backpanel 101 (FIG. 1) is first removed exposing the aligned interfaceportion (“Hardware Locations”, (FIG. 2) of backplane assembly 100. Thefasteners connecting and tightening the alignment interfaces are removedand backplane assembly 100 may be removed from chassis 300.

[0043] In one embodiment the back panel does not have to be removed fromthe backplane module. In this embodiment strategic openings (notillustrated) are placed through the wall of the back panel that allowaccess to the tightening bolts around the alignment pins such that theymay be removed with, perhaps, a specially designed tool. In stillanother embodiment, a portion of back panel 101 may be hinged such thatthe portion swings open exposing alignment interfaces.

[0044] Installing a Backplane Assembly:

[0045] Installation of a backplane assembly is essentially reversed fromremoval. Referring back to FIG. 2 the telescopic fasteners of thetwo-piece assembly are loosened to provide float capability for aligningthe alignment pins to the alignment openings 104 of FIG. 1. Openings 104are only slightly oversize from the alignment pins and not enough tocause miss-alignment of connectors as previously described. Once thealignment pins are engaged through openings 104 of assembly 100, thenthe alignment interfaces are tightened and back panel 101 may bereinstalled. At this point the line and fabric cards may be slid backinto their slots and plugged in using suitable force.

[0046] In one embodiment backpanel 101 is first removed exposing thealignment interface portion of the backplane module. The connecting andalignment fasteners are then loosed and removed allowing the backplanemodule to be removed from the main router chassis.

[0047] It will be apparent to the skilled artisan that there are avariety of alterations that may be made to the embodiments describedherein without departing from the spirit and scope of the invention. Forexample, in one embodiment, instead of optics ferrules, other knownfiber-optics connection mechanisms may be utilized to effect backplaneconnections.

[0048] Providing an optics backplane that is modular and adjustableenables flexibility in maintenance in addition to improved signaltransmission. For example, if an optics backplane assembly requiresservice or testing, a spare backplane module may be fitted to the hostchassis so that it is not out-of-service while it's backplane assemblyis being serviced. The fiber connections may be simply removed andre-routed as well enabling quick re-assignment of communication pathsfor card-to-card communication.

[0049] The present invention may be adapted to routers of same ordifferent manufacture. There are many possible embodiments for providingspecific and optimal backplane schemes. The method and apparatus of thepresent invention should be afforded the broadest scope underexamination. The spirit and scope of the present invention is limitedonly by the language of the claims, which follow.

What is claimed is:
 1. A modular and adjustable backplane assembly toprovide backplane communication between a first signal interface to afirst set of components in a cabinet and a second signal interface tosecond set of components in the same cabinet, comprising: a firstportion mounting a third signal interface configured to engage the firstsignal interface; a second portion mounting a fourth signal interfaceconfigured to engage the second signal interface; an adjustmentmechanism allowing relative movement between the first and secondportions, thereby between the third and fourth signal interfaces, whilepreserving the modularity of the backplane assembly; and a signalconductor assembly engaging the third and fourth signal interfaces tocommunicate signals between the first set of components and the secondset of components.
 2. The backplane assembly of claim 1 wherein thecabinet houses elements of a packet router, and the first and secondsets of components are router cards.
 3. The backplane assembly of claim2 wherein the first and second signal interfaces are groups ofconnectors for connecting signal conductors to individual ones of thecards in the first and second sets of router cards.
 4. The backplaneassembly of claim 1 wherein the first and second signal interfaces arefirst and second connectors to printed circuit boards (PCBs) that are inturn connected to the first and second set of components.
 5. Thebackplane assembly of claim 1 wherein third and fourth signal interfacescomprise fiber-optic connectors, and the signal conductor assemblycomprises one or more fiber-optic fibers having end-connectors forengaging the fiber-optic connectors.
 6. The backplane assembly of claim5 wherein the one or more fibers comprise one or more bundles, ribbonsor cables.
 7. The backplane assembly of claim 1 wherein the third andfourth signal interfaces comprise electrical connectors, and the signalconductor assembly comprises one or more cables of electrical conductorshaving end connectors to engage the electrical connectors.
 8. Thebackplane assembly of claim 4 wherein the signal conductor assemblycomprises a cable of electrical conductors having end-connectors toengage the electrical connectors at the PCBs.
 9. The backplane assemblyof claim 1 wherein the adjustment mechanism comprises telescopicengagement elements allowing adjustment of separation between the firstand second portions.
 10. The backplane assembly of claim 9 wherein theadjustment mechanism further comprises a locking mechanism for securingthe telescoping first and second portions after adjustment to engage thefirst and second interfaces.
 11. The backplane assembly of claim 1wherein the adjustment mechanism further comprises first locatingelements in the immediate area of each of the first and second signalinterfaces, and compatible locating elements in the immediate area ofthe third and fourth signal interfaces, to physically locate the firstand second portions in assembly to the cabinet to engage the first andthird and the second and fourth signal interfaces.
 12. The backplaneassembly of claim 11 wherein the locating elements comprise male andfemale elements for constraining engagement position.
 13. A method forconnecting a first signal interface connected to a first set ofcomponents and a second signal interface connected to a second set ofcomponents in a cabinet, comprising the steps of: (a) preparing amodular and adjustable backplane assembly comprising a first portionmounting a third signal interface configured to engage the first signalinterface, a second portion mounting a fourth signal interfaceconfigured to engage the second signal interface, an adjustmentmechanism allowing relative movement between the first and secondportions, thereby between the third and fourth signal interfaces, whilepreserving the modularity of the backplane assembly, and a signalconductor assembly engaging the third and fourth signal interfaces tocommunicate signals between the first set of components and the secondset of components; and (b) assembling the modular backplane assembly tothe cabinet, with the third signal interface engaging the first, and thefourth signal interface engaging the second, the adjustment mechanismallowing the third and fourth signal interfaces to assume a properseparation distance to accomplish engagement of the signal interfaces.14. The method of claim 13 wherein the cabinet houses elements of apacket router, and the first and second sets of components are routercards.
 15. The method of claim 14 wherein the first and second signalinterfaces are groups of connectors for connecting signal conductors toindividual ones of the cards in the first and second sets of routercards.
 16. The method of claim 13 wherein the first and second signalinterfaces are first and second connectors to printed circuit boards(PCBs) that are in turn connected to the first and second set ofcomponents.
 17. The method of claim 13 wherein third and fourth signalinterfaces comprise fiber-optic connectors, and the signal conductorassembly comprises one or more fiber-optic fibers having end-connectorsfor engaging the fiber-optic connectors.
 18. The method of claim 17wherein the one or more fibers comprise one or more bundles, ribbons orcables.
 19. The method of claim 13 wherein the third and fourth signalinterfaces comprise electrical connectors, and the signal conductorassembly comprises one or more cables of electrical conductors havingend connectors to engage the electrical connectors.
 20. The method ofclaim 16 wherein the signal conductor assembly comprises a cable ofelectrical conductors having end-connectors to engage the electricalconnectors at the PCBs.
 21. The method of claim 13 wherein theadjustment mechanism comprises telescopic engagement elements allowingadjustment of separation between the first and second portions.
 22. Themethod of claim 21 wherein the adjustment mechanism further comprises alocking mechanism for securing the telescoping first and second portionsafter adjustment to engage the first and second interfaces.
 23. Themethod of claim 13 wherein the adjustment mechanism further comprisesfirst locating elements in the immediate area of each of the first andsecond signal interfaces, and compatible locating elements in theimmediate area of the third and fourth signal interfaces, to physicallylocate the first and second portions in assembly to the cabinet toengage the first and third and the second and fourth signal interfaces.24. The method of claim 23 wherein the locating elements comprise maleand female elements for constraining engagement position.
 25. Thebackplane assembly of claim 1 further comprising a fifth signalinterface connected to one or both of the third and fourth signalinterfaces, the fifth signal interface placed on the backplane assemblyto be accessible with the backplane assembly mounted to the cabinet, tofacilitate connection of the backplane assembly to a second backplaneassembly having a fifth signal interface and assembled to a secondcabinet, thereby providing signal communication between components inthe first cabinet and the second cabinet.
 26. The backplane assembly ofclaim 25 wherein the fifth signal interface is a connector forconnecting one or more signal conductors.
 27. The backplane assembly ofclaim 26 wherein the fifth signal interface comprises a fiber-opticconnector compatible with a mating connector for one or more fiber-opticfibers between the backplane assemblies.
 28. The backplane assembly ofclaim 27 wherein the fiber-optic fibers comprise one or more ribbons orcables.
 29. The backplane assembly of claim 26 wherein the fifth signalinterface is an electrical connector compatible with a mating connectorof an electrical cable between the backplane assemblies.